cg300129z_si_013.cif (10.57 kB)
From a Single Molecule to Molecular Crystal Architectures: Structural and Energetic Studies of Selected Uracil Derivatives
dataset
posted on 2012-05-02, 00:00 authored by Katarzyna N. Jarzembska, Marcin Kubsik, Radosław Kamiński, Krzysztof Woźniak, Paulina M. DominiakA comprehensive analysis of crystal packing and energetic
features
of the selected uracil derivatives (i.e., 1-methyluracil, 1,5-dimethyluracil,
5-fluorouracil, 2-thiouracil, 4-thiouracil, 2,4-dithiouracil, and
6-methyl-2-thiouracil) is reported. High-quality X-ray diffraction
data sets of the studied compounds were subjected to the TAAM procedure
(Transferable Aspherical Atom Model based on the Hansen–Coppens
formalism), which gave results comparable both with the optimized
and neutron-diffraction-derived geometries. Crystal packing motifs
were investigated with the aid of Hirshfeld surface fingerprint plots.
Most of the structures form hydrogen-bonded layers kept together by
π-stacking interactions. The only exception is 2,4-dithiouracil,
which exhibits a rather complex 3D network based on N–H···S
and C–H···S contacts. The TAAM procedure allows
also for a quite reliable reconstruction of the electron density distribution
in a crystal structure. It was therefore possible to rationalize the
existence of some F···F interactions in 5-fluorouracil
on the basis of the derived deformation density map. Additional insight
into the nature of crystal architectures was obtained through theoretical
computations, concerning cohesive energy, dimer interaction energy,
and molecule deformation energy evaluation. The balance between molecular
layer stabilization and their mutual interactions is essential for
crystal growth, and thus it is reflected in crystal morphology and
quality. Cohesive energy ranges from −100 kJ·mol–1 for 2,4-thiouracil to about −140 kJ·mol–1 for uracil and 5-fluorouracil, and there is no significant correlation
with the melting point temperature observed. Hydrogen-bonded layers
are more strongly stabilized one with another, when methyl substituents
or sulfur atoms are present. Remarkable differences between 2-thio
and 4-thio derivatives were found and supported by the corresponding
values of aromaticitity indices. Furthermore, the energy calculations
revealed the particular importance of properly determined positions
of hydrogen atoms.
History
Usage metrics
Categories
Keywords
deformation density mapTAAM procedurefluorouracilthiouracilTransferable Aspherical Atom Modeldimer interaction energycrystalelectron density distributionSelected Uracil DerivativesACohesive energy ranges3 D networkMolecular Crystal Architecturesmolecule deformation energy evaluationHirshfeld surface fingerprint plots
Licence
Exports
RefWorks
BibTeX
Ref. manager
Endnote
DataCite
NLM
DC